1. Field of the Invention
The present invention relates to a composite polishing pad and a method for making the same, and more particularly to an adhesive-free composite polishing pad and a method for making the same.
2. Description of the Related Art
Referring to FIG. 1, a schematic view of a polishing device is shown. The polishing device 1 comprises a lower base plate 11, a sheet 12, a polishing workpiece 13, an upper base plate 14, a polishing pad 15 and slurry 16. The lower base plate 11 is opposite to the upper base plate 14. The sheet 12 is adhered to the lower base plate 11 through an adhesive layer 17 and is used for carrying and mounting the polishing workpiece 13. The polishing pad 15 is mounted on the upper base plate 14, faces the lower base plate 11, and is used for polishing the polishing workpiece 13.
The operation mode of the polishing device 1 is as follows. First, the polishing workpiece 13 is mounted on the sheet 12. Then, both the upper base plate 14 and the lower base plate 11 rotates and the upper base plate 14 is simultaneously moved downwards, such that the polishing pad 15 contacts the surface of the polishing workpiece 13. A polishing operation for the polishing workpiece 13 is performed by continuously supplementing the slurry 16 and using the polishing pad 15.
Referring to FIG. 2, an enlarged schematic sectional view of a conventional polishing pad is shown. The polishing pad 15 has a three-layer structure, and includes a cushion layer 151, an adhesion layer 152 and a polishing layer 153. The cushion layer 151 generally has high compression ratio and low hardness, and is fixed on the upper base plate 14. The polishing layer 153 generally has low compression ratio and high hardness, and contacts the surface of the polishing workpiece 13, so as to provide high removal rate and high uniformity. The adhesion layer 152 is a pressure-sensitive adhesive (PSA), and is used for bonding the cushion layer 151 and the polishing layer 153. However, the PSA has low adhesion strength and poor chemical resistance, so that the cushion layer 151 and the polishing layer 153 are easily separated or peeled off from each other, thereby further affecting the progress of polishing.
In another conventional technique, the adhesion layer 152 is a hot-melt adhesive. However, when the hot-melt adhesive is used to perform the composite manufacturing techniques of the polishing pad 15, stress accumulation easily occurs, resulting in deformation of the polishing pad 15.
Additionally, in the above two conventional techniques, the cushion layer 151 and the polishing layer 153 are laminated together by using the adhesion layer 152, so a lamination step is added to the process, thereby increasing the complexity of the process. In this case, the adhesion layer 152 is used additionally, and therefore, a layer of raw material (the adhesion layer 152) is used additionally in the process, thereby increasing the manufacturing costs.
Therefore, it is necessary to provide an innovative and inventive composite polishing pad and a method for making the same to solve the above problems.